Optimal Stratified Placement of Balloons and UAVs to Support Users’ Coverage

Unmanned Aerial Vehicles (UAVs) as wireless base stations are a promising solution to provide better coverage to ground users. In this paper, balloons, UAVs and users are deployed in multiple layers to efficiently enhance users’ coverage. This paper studies three fast deployment problems: (1) placement of balloons to aid UAVs for wireless assistance, (2) placement of UAVs to provide coverage to users and (3) a joint problem for successful deployment of balloons, UAVs and connectivity to users. In the first part of the problem, an optimization problem is designed to minimize the number and costs of balloons. In the second part, the goals are to minimize the number of UAVs, maximize the number of users’ connections, minimize the distance between users and UAVs, and minimize the UAVs’ deployment costs. Additionally, a joint problem is also introduced to provide efficient wireless coverage. The problem is formulated as an Integer Linear Program (ILP). An optimal algorithm is applied to solve the optimization problem. Considering the computational complexity of solving the problem optimally, a low complexity greedy algorithm is proposed. Simulation results show the efficiency of the proposed optimal and greedy algorithms. We show that our proposed optimal is minimizing an overall objective function in better way than the heuristic.